Phishing is an attempt by a fraudster to obtain sensitive information from computer users by masquerading as a trustworthy entity in an electronic communication. In one conventional scheme, the fraudster sends emails which appear to be from the trustworthy entity indiscriminately to a large number of computer users. Such emails typically contain a manipulated link to the fraudster's website (i.e., a spoof website which appears to be the website of the trustworthy entity) and instruct the computer users to go to that website using the link to perform various operations (e.g., login, update user information, change passwords, confirm accounts, etc.). Once a computer user goes to the fraudster's website and follows the instructions, the fraudster is able to exploit that computer user (e.g., load malicious code onto the user's computer, login to an actual trustworthy entity as that computer user, etc.).
To protect computer users against phishing attacks, general warnings are often provided to the computer users informing them to avoid emails that (i) include links and (ii) instruct the computer users to click on the links to access websites. When a particular email has been identified as an actual phishing attack (e.g., due to the wide distribution and long lasting prevalence of that email), a precise warning may be provided to the computer users informing them to avoid that particular email if it is received (e.g., to not follow instructions in that email and to immediately delete that email if that email is received).
Spear phishing is similar to phishing but targets specific computer users. For example, the fraudster may be able to obtain personal information about a specific computer user (e.g., the name of that computer user's bank, the name of a friend or family member, etc.), and then include that personal information in a custom email to that computer user in hope that the demonstrated familiarity with that personal information convinces that computer user that the email is not a hoax. The personal information may come from a variety of sources including the specific computer user's social network, knowledge of the specific computer user's title/position at a company, a phone call to the specific computer user's place of business, etc. Also, a spear phishing email may solicit activation of an executable file and thus insert malware into an organization.